Can a human cleanly throw a baseball through a pizza box

Factual Questions
161

Well I understand now why we’re talking past each other. In your response to my post #138, you did not use the term freefall and I didn’t infer that from your context, so I didn’t realize that’s what you were talking about. And I think it should have been clear from my post that is not what I was talking about.

The first three paragraphs of my post were explaining to Sinisterniik how thrown objects don’t really ‘‘hang’’ in the air but that there is a small time period near the apex where the object is moving very slowly that it can be treated in a simplified manner as stationary.

I clearly stated that I was assuming the bottle was hit during that time period, as it looks like it is on the video, even saying we could pretend the bottle was hanging from a string until it was hit. The bottle of course has no memory of how it got to that point and no ability to see into the future about where it will be going. At that point the bottle is merely a slow moving, near stationary object.

Furthermore, my ball analogy had people standing stationary by a cliff. I surely wouldn’t have made that comparison if I had been talking about a bottle exploding during freefall. If I had been, I would have started off saying something like ‘‘Imagine three skydivers in freefall who each throw a ball…’’

Having reiterated my assumptions, what issue do you still take with what I said? Do you disagree that the bottle was hit close to its apex when it was moving very slowly and not in highspeed freefall? Would you agree that a thrown bottle exploding at or very near its apex would look different from one exploding during comparatively high speed freefall?

I’m still not following you here. In the absence of gravity, the balls will continue to move in the direction they were initially thrown. The first ball would hit the ground, the second ball would continue parallel to a flat earth, and the third would forever continue in the direction away from the earth. How are those relative positions the same as if the balls were acted upon by gravity? And I’m talking about them being thrown from an initially stationary position, consistent with everything I’ve written so far, and not being thrown while in some kind of freefall.

162

When was this home run hit? If it was in the last 10 or 20 years, I would not assume that the microphone is in the same place as the camera.

Here is a video of Babe Ruth hitting a ball in the 1920s:

If you skip forward to about 0:33 and watch and listen, there is a very noticeable delay between the image of the bat hitting the ball and the cracking sound. It’s hard to tell where the microphone is in that shot, but I would guess it’s in the same place as the camera and that it’s somewhere behind the third base line. ETA: But in front of the stands.

163

Well this is weird - for the last two days I was able to step through the video a frame at a time using the cursor keys as I described. But this morning when I try to do that the video jumps several seconds at a time with each key press.

WTF? Did they just change their player in the last 12 hours? Oddly enough, a google search on the relevant terms brought this thread up as the 3rd result.

Guess if I want to go frame by frame in the future I’ll have to jump through the hoops to watch the video in a different player. Stupid youtube.

I was thinking the same thing. :slight_smile:

164

Someone can correct me if I’m wrong, but I’m pretty sure sound travelled much slower back in the old days. High speed sound wasn’t introduced until much later, around when they came out with color tv if I recall correctly.

On a serious note, is there any way to know if that video is playing the actual original soundtrack under the voice-over? Could the bat hitting the ball sound, and the crowd, etc. just be effects added for that video?

165

I can’t speak to the rest of your post, but I can assure you from personal experience that this is blatantly false. I suggest you go to Six Flags in NJ and ride the Freefall.

166

I am not sure how else to explain this without using math–which I’m not opposed to doing, it’s just that I don’t actually know the math. I just know the concepts. :wink:

I’ll see if I can get a physicist (or otherwise knowledgable) Doper to chime in, but meanwhile, I’ll try again at the conceptual level.

First the short version: Gravity acts identically on all the balls, imparting identical accelerations on each. This I am sure you know. But since it imparts an identical acceleration on each, it cannot change their positions relative to each other.

Now the long version, typed under some time pressure so sorry if it could be written up more clearly:

Just think about two balls to keep it simple. I throw one upwards, and one downwards, off a cliff. Gravity acts on both balls–and it acts equally on both balls. In other words, whatever downward motion it imparts to one ball, it also imparts to the other ball. In other words, the same quantity of downward acceleration is being added to both balls. Right?

Okay, now imagine this happening without gravity. Say I throw one ball upwards at a speed of 5 units per second, and the other one downwards at a speed of five units per second. So after one second, the balls are 10 units away from each other. At two seconds, they are 20 units away from each other. And so on.

My claim is that these distances would be the same even in a gravitational field. In other words, when I throw the two balls off the cliff in the same way, then after one second, they’ll be 10 units away from each other, after two seconds, 20 units away from each other, and so on–until one of them hits the ground of course.

My argument for this is as follows. Since gravity imparts an identical downward acceleration on both balls, we can simply represent that acceleration with a variable “x.” So then, if after one second the balls would have been 10 units away from each other without gravity, then after one second in gravity, since each ball’s position would be it’s old position minus x*, their positions would still be 10 units away from each other. For call each balls position without gravity P1 and P2 respectively. Their positions with gravity, then, would be P1 minus x, and P2 minus x, respectively. But (P1 - x) - (P2 -x) == P1 - P2. In other words, their positions relative to each other are the same whether there is a gravitational field present or not.

*Actually minus x multiplied by a time factor or something or other but that factor is the same for both balls so it doesn’t matter.

167

Try it in a box in a vacuum with no view to the outside and you’ll see that it’s true. This isn’t a controversial claim, it’s basic physics.

You do know how they use airplanes in freefall to simulate gravityless situations, don’t you?

168

And just to reiterate the relevance to the exploding bottle–since the balls would have the same position relative to each other both in freefall, when thrown off the cliff, at the apex of a situation in which the thrower has been tossed, and so on, it follows that (abstracting from aerodynamic concerns) the bottle’s explosion would have the same shape in all those situations as well. The fact that it is in a gravitational field should not affect the shape of the explosion.

169

Sniisterniik, so you’ve been in a freefalling box. Have you ever been in space in zero gravity? If not, what’s your basis for comparison?

You know how it feels to be in that falling box. Well, that’s how it feels to be in deep space, too.

170

OK, you left out the vacuum part. And airplanes in freefall have to be under certain conditions to simulate gravityless situations as well.

171

Sorry to multipost, but to reiterate the argument:

I believe you are saying an explosion in a gravitational field should have a different shape from an explosion outside a gravitational field.

I am arguing that, since a system in freefall is indiscernible from a system inside a gravitational field, an explosion in freefall would have the same shape as an explosion outside a gravitational field.

The explosion depicted in the video takes place in freefall. Hence it should be shaped like an explosion taking place outside any gravitational field. And you’re saying that’s exactly what it is shaped like. So I’m saying that what you’re saying you’re seeing is exactly what you should expect to see if the explosion is taking place, as depicted, within a gravitational field.

172

??? It escapes me how you could possibly have thought I didn’t intend those very presuppositions. (Even if itweren’t obvious on simple conversationally pragmatic grounds–which I think it should have been–still, I’ve been saying, out loud, “abstracting from aerodynamic concerns” all along fer cryin’ out loud…)

But anyway guess I’m glad it’s cleared up.

(BTW whatever “special conditions” you’re referring to concerning the airplane, they must basically add up to just being sure the plane really is in freefall. Because once it’s in freefall, boom, gravity (apparently to observers inside) goes away. No other condition is necessary.)

173

I just reread this and noticed you’re using “freefall” differently than I am. You’re characterizing the bottle explosion as not occuring in freefall. But it is. Once the bottle leaves the guy’s hands, it’s in freefall til it hits the ground. Yes, even while it’s moving upwards–even then, it is in freefall.

There is no difference betewen freefall and “high speed freefall” in this context. The effects are the same in both cases–namely, there is no differential effects on different parts of the system in freefall based on the local gravitational field.

Okay I shall resolve to post no more til someone replies because I’ve posted a ridiculous number of times. Sorry about that!

ETA: Wikipedia article on free fall here. I haven’t read it, but in my experience wikipedia articles on topics like these are good sources of basic information.

174

I don’t think there’s any way to know. I do think that a delay of 40 milliseconds is noticable. I’m not an expert, it’s just based on my experience.

175

You’re definitely not the only one doing that in this thread. :stuck_out_tongue:

176

I don’t know what the threshold is, but the microphone placement is everything. The best way to mic a live concert involves a large amount of mics in different positions next to the stage. However, in a lot of orchestral videos the mics are placed farther back to A) aid in mixing such a large variety of sounds and to B) keep from obstructing the view of patrons that have paid sometimes hundreds of dollars for their seats. In these cases, there is a significant delay between the initial sound and what the viewer hears.

I cued this up right to an obvious spot.

177

Based on some quick research, I’d say the throwing distance was less than 25 feet. The group is standing on the infield dirt behind second base, and the objects are tossed near second. In high school baseball (and above), the infield dirt is a 95’ radius from the pitching rubber, which means it extends about 28’ past second.

There’s also an almost continuous shot of the little blonde girl running to look at the pizza box. She takes about 8 strides, and when I tried to imitate her strides (out on my deck just now) I covered less than 20 feet.

So, the video was presumably shot wide angle, and the actual throwing distance is only about the length of a living room – well under half the distance of an actual major league pitch.

178

I came up with the same distances you did using the same references. This would be no big deal for a ML pitcher. It would be far more difficult to fake.

179

Read through that and it didn’t help me any - just basic stuff I already knew and things I didn’t see as applicable to our specific conversation. However this may have helped me turn the corner:

Now I think I’m starting to smell what you’re stepping in. Gotta keep thinking on this till I can really wrap my head around it but I think you’ve got me pointed in the right direction.

Not bugging me in the least - I appreciate the replies and thanks for fighting my ignorance even if it took longer than you thought. :slight_smile:

180

Not everyone in the fake camp thinks that he couldn’t throw a ball and hit the tossed objects. Some think (or at least I do and I’m not going back through the thread to tally it up) that the effects of the collision are what is not realistic.

If those effects turned out to be not possible, then faking it would be the only way to go, regardless of difficulty. And I don’t think these days it would be all that difficult for them to fake, considering all the fake stuff you see on commercials, in the movies, etc.

So for the record, I think he could throw a ball and hit those things.